I had an Anthem amp (MCA-5, the predecessor to the 50) paired with Paradigm Reference Studio's (40's, 20's and CC) and felt the combo was just a tad too forward to my tastes. That may be to your liking, but from what I have heard from Sherbourn/Paradigm owners, that combo is better situated together.

I would also recommend the Sherbourn, that's what I have driving my Paradigms. But if at all possible you should try both amps in your system. People have different preferences and it is entirely possible that you could prefer the Anthem over the Sherbourn.

I think MSRP on the 5/5120 is around $2.1K, I don't know what the street price is.

FYI, 5/1500 and 5/1500A are the older models, but the basic design is almost identical to the current 5/5120. Not many hit the used market and when they do they generally sell pretty quick. But if you find one they are typically about $1-$1.1K for the 1500 and $1.1-$1.3 for the 1500A.

Count another vote for the Sherbourn. I have the now-discontinued 5/1500A model driving my Paradigm Studio 80s, Studio CC, and Studio 20s, and it is awesome. I would agree that Anthem + Paradigm Studio is a bright combo, but that's just to my ears. Your ears might enjoy that combo.